sync.c

Purpose

Cross-platform mutexes, rwlocks, atomic helpers and a tiny bar/ack primitive.

API Reference

void xusleep(uint32_t nUsecs)

• Arguments:
  • microseconds to sleep.
• Does:
  • sleeps with usleep() on POSIX.
  • uses millisecond-granularity Sleep() on Windows.
• Returns:
  • no return value.

void XSync_Init(xsync_mutex_t *pSync)

void XSync_Destroy(xsync_mutex_t *pSync)

void XSync_Lock(xsync_mutex_t *pSync)

void XSync_Unlock(xsync_mutex_t *pSync)

• Arguments:
  • mutex object.
• Does:
  • initializes a recursive mutex / critical section and controls it.
  • operations are skipped when bEnabled == XFALSE.
• Returns:
  • no return value.
• Failure behavior:
  • initialization, destroy, lock and unlock errors print to stderr and terminate the process.

void XRWSync_Init(xsync_rw_t *pSync)

void XRWSync_ReadLock(xsync_rw_t *pSync)

void XRWSync_WriteLock(xsync_rw_t *pSync)

void XRWSync_Unlock(xsync_rw_t *pSync)

void XRWSync_Destroy(xsync_rw_t *pSync)

• Arguments:
  • rwlock object.
• Does:
  • initializes, locks, unlocks and destroys a read/write lock.
  • Windows tracks whether the held lock is exclusive so unlock can release the correct SRW mode.
• Returns:
  • no return value.
• Failure behavior:
  • underlying OS failures print to stderr and terminate the process.

void XSyncBar_Bar(xsync_bar_t *pBar)

void XSyncBar_Ack(xsync_bar_t *pBar)

void XSyncBar_Reset(xsync_bar_t *pBar)

• Arguments:
  • bar/ack state object.
• Does:
  • set bar and clear ack, set ack, or clear both flags.
• Returns:
  • no return value.

uint8_t XSyncBar_CheckBar(xsync_bar_t *pBar)

uint8_t XSyncBar_CheckAck(xsync_bar_t *pBar)

• Arguments:
  • bar/ack state object.
• Does:
  • reads the atomic flag.
• Returns:
  • XSTDOK when the flag is set.
  • XSTDNON otherwise.

uint32_t XSyncBar_WaitAck(xsync_bar_t *pBar, uint32_t nSleepUsec)

• Arguments:
  • bar/ack state object.
  • optional sleep interval between polls.
• Does:
  • busy-waits until ack becomes set.
• Returns:
  • approximate waited microseconds.

Important Notes

• These primitives are designed for internal runtime code, not for failure-tolerant library boundaries.
• On Windows, xusleep() rounds sub-millisecond waits up to at least 1 ms.